A detachable, foldable seat specially designed to attach to the tailgate of a pickup truck or sport utility vehicle. The device comprises a bench seat, having a bottom seat cushion and a back support cushion attached to a hinge mechanism with a tailgate jamb post. The seat can fold in half at the hinge between the bottom and back support cushion of the device. During installation, the jamb post of the hinge inserts into the jamb between the open tailgate and the truck bed, securing the seat in position. A dual purpose strap attaches to either side of the bottom cushion such that the strap wraps around the open tailgate and further secures the seat in place. When the device is uninstalled and in a closed configuration, the strap serves as a fastening strap to keep the device in a stowed position.